Healthcare provider holding urine sample to check for kidney infection vs. UTI

Kidney Infection vs. UTI: What's the Difference?

Medically reviewed on May 19, 2023 by Karen Janson, MS, MD. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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UTIs, urinary tract infections, and kidney infections are both conditions that impact the urinary system, but they have several important differences in symptoms, severity, and treatment.

UTIs commonly refer to infection of the lower urinary tract, or the urethra and bladder. These infections occur frequently, affecting an estimated 40% to 60% of people assigned female at birth at least once in their lives. [1] In general, they tend to be relatively mild and respond well to treatment with the help of a healthcare provider.

Kidney infections are a more serious type of UTI that progresses from an infection of the lower urinary tract, up to the kidneys. [8] Kidney infection symptoms can be much more uncomfortable and require prompt medical intervention to assess and treat. If neglected, a kidney infection can lead to severe health complications.

Knowing the differences between UTIs and kidney infection is an important step in caring for your urinary health and seeking treatment. Below, we’ll map out their causes, the symptoms that distinguish a kidney infection vs. UTI, and treatment options to help put you on the road to recovery.

Understanding the Difference Between UTIs and Kidney Infections

Healthcare providers recognize three main types of UTIs, two involving the lower urinary tract and one including the upper urinary tract, graded depending on how much of the urinary system is impacted. These infections include: [3]

  • Urethritis, or an infection of the urethra. The urethra is the passageway where urine flows from the bladder to exit the body. It’s the lowest area that can be affected by an infection.
  • Cystitis, or an infection of the bladder. At this stage, a UTI has progressed from the urethra and deeper into the urinary system.
  • Pyelonephritis, or an infection of the kidneys or upper urinary tract. Pyelonephritis may be caused by ascending bacteria in the urinary tract. It may also be caused by vesicoureteral reflux, or the back-and-forth flow of urine between the bladder and kidneys. A blockage in the urinary tract from a kidney stone can also increase the risk of developing pyelonephritis. This is the most advanced stage of a UTI.

What Causes a UTI?

Many factors can play a role in admitting bacteria to the urethra and initiating a UTI. Some contributing factors include: [4]

  • Having female anatomy – People assigned female at birth have a shorter urethra than people assigned male at birth. Their urethras are also physically closer to their anus, where bacteria, such as E. coli reside. For these reasons, it can be easier for bacteria to travel to and infect the urethra.
  • Being sexually activeCan a UTI be transmitted through sex? If you have sex, you may increase the likelihood of spreading bacteria like E. coli from other areas of the body to the urethra.
  • Having an impaired immune system – UTIs are a type of bacterial infection, and people who are immunosuppressed are at a higher risk of acquiring an infection.
  • Going through menopause – Many hormonal changes occur during menopause, including a reduction in estrogen production. Reduced estrogen may change the pH and balance of bacteria in the genitourinary area and heighten some people’s risk of contracting an infection. [1]
  • Using certain types of birth control – Diaphragms and spermicide have been associated with an elevated risk of UTIs. [4]
  • Using a catheter – Catheters are widely used during labor, after surgery, and in other circumstances to help people urinate if they can’t do so on their own. However, catheters can introduce bacteria into the urinary system and create a potential bacterial infection. [1]

Symptoms of a Lower UTI

If you experience symptoms of a bladder infection or lower UTI, you may notice: [1,2]

  • Making frequent or urgent trips to the bathroom (frequency, urgency)
  • Discomfort or burning while urinating (dysuria)
  • Passing only a small amount of urine when urinating
  • Difficulty starting the urine stream when going to the bathroom (hesitancy)
  • Urine that carries an odor
  • Urine that appears cloudy or discolored with blood (pyuria or hematuria)
  • Pressure or pain around the pelvic region or lower abdomen

What Causes a Kidney Infection (Pyelonephritis)?

Most kidney infections progress from a lower UTI that has not yet been treated or has not responded well to treatment. [7] In other circumstances, a kidney infection can result from:

  • A viral infection [8]
  • Another infection in the body that has penetrated the bloodstream and spread to the kidneys [7]

Because they often have the same etiology, UTIs and kidney infections share many of the same risk factors: having female reproductive anatomy, going through menopause, and so on. However, you may be more susceptible to a kidney infection if: [8]

  • You have had a UTI in the last year
  • Are pregnant
  • Have a kidney stone
  • Have diabetes
  • Have an immune disorder
  • Have urinary retention (difficulty emptying the bladder when urinating)
  • Have nerve damage surrounding your bladder
  • Have a history of spinal cord injury
  • Have certain anatomical attributes, like a narrower-than-average urethra or an enlarged prostate.

Symptoms of a Kidney Infection

Like their causes, many symptoms of kidney infection overlap with UTI symptoms. When a UTI has progressed to the kidneys, however, you may also experience: [8]

  • Fever
  • Body chills
  • Nausea
  • Vomiting
  • Pain around the flank(s) or lower back

If you notice any of these symptoms, it’s important to reach out to your healthcare provider as soon as possible to begin a course of treatment. Left untreated, kidney infections can lead to: [4]

  • Hypertension
  • Sepsis
  • Kidney scarring or structural damage
  • Chronic kidney disease
  • Kidney failure

Treating a UTI

Can a UTI go away on its own? In some cases, the immune system can take care of a UTI on its own, eliminating the need for treatment. [1] However, if you’re wondering, “Why do I keep getting UTI,” it’s common to experience recurring UTIs: roughly 25% of people assigned female at birth who develop a UTI will have another one within 6 months. [1]

To eliminate symptoms and reduce the risk of further progression, however, UTIs are treated with a course of antibiotics, most commonly: [1]

  • Trimethoprim/Sulfamethoxazole
  • Cephalosporins
  • Fosfomycin
  • Nitrofurantoin

In addition to antibiotics, your healthcare provider may recommend implementing some lifestyle habits to help prevent the spread of bacteria to the urethra. Healthy practices include:

  • Drinking plenty of fluids, especially water, to flush the urinary tract
  • Voiding every 3-4 hours when awake
  • Emptying the bladder before and after having sex
  • Using a “front to back” motion to wipe after using the restroom

How Long Does It Take to Heal a Lower UTI?

After starting treatment, symptoms of a bladder infection may recede in a matter of a few days.4 However, it is extremely important to complete the prescribed antibiotic protocol even if you notice a cessation of symptoms. [1] Stopping your antibiotics prematurely may contribute to a relapse of UTI symptoms and antibiotic resistance, which could make you less responsive to future treatment. [10]

Treating a Kidney Infection

Treatment protocols for pyelonephritis vary depending on the cause and severity of the infection. In less severe cases, kidney infections are treated with antibiotic medication either orally or intravenously (with an IV). [9]

Your healthcare provider may run tests to see if your infection can be attributed to a particular strain of bacteria. That way, they can refine your antibiotic protocol to deal with that specific strain (rather than all of the bacteria that may infect your urinary system). [9]

Do Kidney Infections Require Hospitalization?

Being diagnosed with a kidney infection can be scary, but in most cases, you will not have to stay in the hospital to be treated.

However, more complex circumstances may require hospitalization and more aggressive therapy. For instance, if your infection resulted from kidney stones, you may require treatment to remove them as well as antibiotics to alleviate the infection.

How Long Does It Take to Heal a Kidney Infection?

In most cases, kidney infection symptoms begin to recede within several days of taking antibiotics.

However, the duration of antibiotic courses prescribed may differ between individuals, diagnoses, and healthcare providers. Antibiotic courses may last for several days to several weeks. [7] If your kidney infection requires treatment at the hospital, it is likely you’ll need more time to recover.

Everlywell: Keep Up with Your Health from Home

UTIs and urinary health in general aren’t often discussed, and it’s normal to feel confused about how to read the cues your body is sending you.

If you think you have a UTI, speak with a licensed healthcare provider through Everlywell. Our licensed clinicians will meet with you virtually to help diagnose your symptoms, and if needed, can provide online UTI treatment.

Take a proactive approach to your well-being by exploring Everlywell’s virtual care services today.

How to Prevent UTIs

Causes and Treatments of a UTI During Pregnancy

Why Do I Keep Getting UTIs?


  1. Urinary Tract Infection. StatPearls [Internet]. November 28,2022. URL. Accessed May 11, 2023.
  2. Urinary Tract Infections. Cleveland Clinic. URL. Accessed May 11, 2023.
  3. Types of Urinary Tract Infections. Stanford Medicine Health Care. URL. Accessed May 11, 2023.
  4. Urinary Tract Infection (UTI). Mayo Clinic. URL. Accessed May 11, 2023.
  5. Recurrent extended-spectrum beta-lactamase-producing Escherichia coli urinary tract infection due to infected uterine device. February 2014. Singapore Medical Journal. URL. Accessed May 11, 2023.
  6. Asymptomatic Bacteriuria. American Family Physician. July 15, 2020. URL. Accessed May 11, 2023.
  7. Kidney infection. Mayo Clinic. URL. Accessed May 11, 2023.
  8. Definition & Facts of Kidney Infection (Pyelonephritis). National Institute of Diabetes and Digestive and Kidney Diseases. URL. Accessed May 11, 2023.
  9. Treatment for Kidney Infection (Pyelonephritis) - How do health care professionals treat kidney infections? National Institute of Diabetes and Digestive and Kidney Diseases. URL. Accessed May 11, 2023.
  10. National Library of Medicine. Antibiotic Resistance. URL. Accessed May 11, 2023.
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